1. Field of the Invention
This invention relates to a method for the production of a sulfide group-containing thiol compound. More particularly, it relates to a method for the production of a sulfide group-containing thiol compound by the ring-opening addition of an alkylene sulfide to a thiol compound.
The sulfide group-containing thiol compounds which are obtained by the method of this invention are useful compounds which find extensive utility in a chelating agent, a lubricant additive, an additive for rubber, an additive for the oil refining treatment, a polymerization chain transfer agent, and etc.
2. Description of the Related Art
As respects methods for producing a sulfide group-containing thiol compound by the ring-opening addition of an alkylene sulfide to a thiol compound, a method for causing this reaction without using a catalyst was disclosed long ago in German Patent No. 696,774. This method, however, necessitates an elevated temperature. To solve this problem, U.S. Pat. No. 2,490,984 and U.S. Pat. No. 2,497,100 propose methods which use sodium alkoxide and boron trifluoride respectively as a catalyst. Further, methods using alkali metal alkoxides as a catalyst are disclosed in J. Am. Chem. Soc. (1947), Vol. 69, p. 2675, J. Chem. Soc. (1948), p. 1894, and J. Chem. Soc. (1949), p. 282. Though these catalysts have high activity, they have the problem of manifesting low selectivity for the products aimed at because the alkylene sulfides themselves as a raw material are liable to be polymerize.
Izv. Akad. Nauk. SSSR, Ser. Khim. (1975), No. 3, p. 660 and U.S. Pat. No. 4,163,832 discloses a method which uses amine compounds such as trimethyl amine and triethyl amine or trimethyl phosphine as a catalyst. JP-B-07-5,585 discloses a method which effects the reaction in an aqueous sodium hydroxide solution-benzene system using benzyl trimethyl ammonium chloride as a catalyst. The methods mentioned above are invariably liable to induce the polymerization of alkylene sulfide as a secondary reaction and, particularly when ethylene sulfide is used as a raw material, incur difficulty in preventing the ethylene sulfide from being polymerized.
As described above, although numerous reports published to date have covered methods for obtaining a sulfide group-containing thiol compound by the ring-opening addition of an alkylene sulfide to a thiol compound, these methods have intolerable defects. A method capable of selectively producing a sulfide group-containing thiol compound aimed at has not yet been brought into being.
An object of this invention, therefore, it to provide a novel method for producing a sulfide group-containing thiol compound.
Another object of this invention is to provide a method for producing a sulfide group-containing thiol compound with high selectivity without entailing polymerization of alkylene sulfide.
Yet another object of this invention is to provide a method for producing a sulfide group-containing thiol compound using a solvent capable of effecting the ring-opening addition reaction with high selectivity without inducing the polymerization of alkylene sulfide.